Liquid duct for an electrowetting display

ABSTRACT

A method for fabricating an electrowetting display may include depositing a sacrificial layer on a support plate, etching portions of the sacrificial layer to form liquid duct forms on the support plate, depositing a photoresist layer on the liquid duct forms and the support plate, etching portions of the photoresist layer to form a spacer grid, and removing the liquid duct forms to form liquid ducts between the support plate and the portions of the spacer grid.

PRIORITY

This application is a continuation of, and claims priority to, U.S.patent application Ser. No. 14/574,216, filed on Dec. 17, 2014, thecontents of which are hereby incorporated by reference.

BACKGROUND

Electronic displays are found in numerous types of electronic devicessuch as electronic book (“eBook”) readers, cellular telephones, smartphones, portable media players, tablet computers, wearable computers,laptop computers, netbooks, desktop computers, televisions, appliances,home electronics, automotive electronics, augmented reality devices, andso forth. Electronic displays may present various types of information,such as user interfaces, device operational status, digital contentitems, and the like, depending on the kind and purpose of the associateddevice. The appearance and quality of a display may affect a user'sexperience with the electronic device and the content presented thereon.Accordingly, finding ways to enhance user experience and satisfactioncontinues to be a priority. Moreover, increased multimedia use imposeshigh demands on designs, packaging, and fabricating display devices, ascontent available for mobile use becomes more extensive and deviceportability continues to be a high priority.

An electrowetting display includes an array of pixels individuallybordered by pixel walls that retain liquid, such as opaque oil, forexample. Light transmission through each pixel is adjustable byelectronically controlling a position of the liquid in the pixel.Resolution and quality of an electrowetting display may depend on anumber of factors, such as optical transmissivity or reflectivity ofmaterial layers of the electrowetting display and pixel size, just toname a few examples.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description is set forth with reference to the accompanyingfigures. In the figures, the left-most digit(s) of a reference numberidentifies the figure in which the reference number first appears. Theuse of the same reference numbers in different figures indicates similaror identical items or features.

FIG. 1 illustrates a cross-section of a portion of an electrowettingdisplay, according to some embodiments.

FIG. 2 is a perspective view of a portion of a spacer grid, according tovarious embodiments.

FIG. 3 is a top view of a portion of an electrowetting display device,illustrating a spacer grid, according to various embodiments.

FIGS. 4-6 are cross-sectional views of a portion of a spacer grid,according to various embodiments.

FIGS. 7-9 are cross-sectional views of a portion of a spacer grid,illustrating various shapes of liquid ducts, according to embodiments.

FIG. 10 is a cross-sectional view of a portion of an electrowettingdisplay, according to various embodiments.

FIG. 11 is a top view of a portion of an electrowetting display device,illustrating a spacer grid, according to various embodiments.

FIG. 12 is a perspective view of a portion of a spacer grid, accordingto various embodiments.

FIGS. 13-16 illustrate portions of a process for fabricating anelectrowetting display, according to some embodiments.

FIGS. 17-21 illustrate portions of a process for fabricating anelectrowetting display, according to other embodiments.

FIG. 22 is a flow diagram of a process for fabricating an electrowettingdisplay, according to various example embodiments.

FIG. 23 illustrates an example electronic device that may incorporate adisplay device, according to some embodiments.

DETAILED DESCRIPTION

In various embodiments described herein, electronic devices includeelectrowetting displays for presenting content and other information. Insome examples, the electronic devices may include one or more componentsassociated with the electrowetting display, such as a touch sensorcomponent layered atop the electrowetting display for detecting touchinputs, a front light or back light component for lighting theelectrowetting display, and/or a cover layer component, which mayinclude antiglare properties, antireflective properties,anti-fingerprint properties, anti-cracking properties, and the like.Various embodiments described herein include structures that may beincluded in electrowetting displays and techniques for fabricating suchstructures.

In some embodiments, an electrowetting display includes a first supportplate and an overlying second support plate and a plurality of pixelregions therebetween. Each of the pixel regions may include one or morehydrophobic surfaces, an oil, and an electrolyte solution at leastpartially surrounding the oil. Portions of pixel regions may bepartitioned or delineated from one another by pixel walls disposed onthe first support plate. A spacer grid that mechanically connects thefirst support plate with the second support plate, or which forms aseparation between the first support plate and the second support plate,contributes to mechanical integrity of the electrowetting display.Herein, unless otherwise indicated, a viewing side of an electrowettingdisplay is not limited to the side of the display that includes eitherthe first support plate or the second support plate.

A spacer grid incorporated in an electrowetting display contributes tothe mechanical integrity of the electrowetting display. In particular, aspacer grid allows for a relatively large amount of surface area of asecond support plate to be mechanically supported by the spacer grid.This is in contrast to a relatively small amount of surface area of thesecond support plate mechanically supported by individual spacers thatare columns or pillars. These spacers are generally disposed at variouslocations (e.g., at pixel wall intersections) across an array of pixelregions of an electrowetting display. Though a spacer grid may providemore strength than columnar-type spacers, a spacer grid may tend toblock flow of electrolyte solution among the pixel regions. Such flow,for example, may be important during a fabrication process when a bottomportion of an electrowetting display is joined to a top portion of theelectrowetting display and excess electrolyte solution therebetween issqueezed out from the assembly. Accordingly, embodiments herein describea spacer grid that includes liquid ducts, which allow electrolytesolution to flow through the liquid ducts in the spacer grid among pixelregions. For example, a liquid duct may comprise an opening or channelin a portion of the spacer grid between adjacent pixel regions. Such anopening may be bordered by the second support plate, for example.

During a fabrication process, the first support plate may be laminatedor otherwise coupled to a second support plate by a rolling process, forexample. During such a process, excess electrolyte solution may besqueezed out from between the first support plate and the second supportplate. Excess electrolyte solution may flow through liquid ductssituated at or near top portions of the spacer grid, relatively farabove the oil. Because of this distance between the liquid ducts,through which excess electrolyte solution flows, and the oil, a tendencyof flowing excess electrolyte solution to disturb (e.g., drag) the oilwill be reduced.

In some embodiments, a spacer grid may be joined to tops of pixel wallsdisposed on a first support plate. Herein, “joined” elements need not beglue or adhered to one another, but may merely be placed in contact withone another or may be adjacent to one another with a relatively smallgap therebetween, for example. After assembly of an electrowettingdisplay that includes first and second support plates, the spacer gridmay add to the height of the pixel walls disposed on the first supportplate. The resulting extra wall height provides a number of benefits.For example, extra wall height may help prevent oil from “spilling” overpixel walls from one pixel region to an adjacent pixel region. Suchspilling may potentially occur as a result of physical shock (e.g.,external impact) imposed on the electrowetting display device, forexample. Such spilling may also occur if a pixel is operated with adriving voltage that is relatively large, with or without thecombination of a physical shock imparted on the electrowetting displaydevice. In this case, oil may be displaced “tightly” against pixel wallstoward an edge of the pixel. Because forces inducing such displacementare primarily in a horizontal (e.g. parallel with the support plates)direction, the displaced oil tends to be squeezed in an upward directionalong the pixel walls resulting in a relatively tall bead of oil. Such atall bead of oil may spill over the pixel walls. Adding a spacer grid toincrease the overall height of the pixel walls may prevent suchspillover, thus allowing pixels to be operated at relatively largedriving voltages, which can improve brightness and contrast ratio of anelectrowetting display.

In a number of embodiments, a display device, such as an electrowettingdisplay device, may be a transmissive, reflective or transflectivedisplay that generally includes an array of pixels (e.g., or subpixels)configured to be operated by an active matrix addressing scheme. Forexample, rows and columns of electrowetting pixels are operated bycontrolling voltage levels on a plurality of source lines and gatelines. In this fashion, the display device may produce an image byselecting particular pixels to at least partly transmit, reflect orblock light. Pixels are addressed (e.g., selected) via rows and columnsof the source lines and gate lines that are electrically connected totransistors (e.g., used as switches) included in each pixel. Transistorstake up a relatively small fraction of the area of each pixel. Forexample, the transistor may be located underneath the reflector inreflective displays. Herein, a pixel may, unless otherwise specified,comprise a single subpixel or a pixel that includes two or moresubpixels of an electrowetting display device. Such a pixel or subpixelmay be the smallest light transmissive, reflective or transflectiveelement of a display that is individually operable to directly controlan amount of light transmission through and/or reflection from theelement. For example, in some implementations, a pixel may be a pixelthat includes a red subpixel, a green subpixel, and a blue subpixel. Inother implementations, a pixel may be a pixel that is a smallestcomponent, e.g., the pixel does not include any subpixels.

Electrowetting displays include an array of pixels comprising pixelsand/or subpixels sandwiched between two support plates, such as asubstrate and a top plate. For example, the substrate may be a firstsupport plate that, in cooperation with the top plate (the secondsupport plate), contains pixels that include oil, electrolyte solution,and pixel walls between the support plates. Support plates may includeglass, plastic (e.g., a transparent thermoplastic such as PMMA or otheracrylic), metal, semiconductor material, or other material and may bemade of a rigid or flexible material, for example.

Pixels include various layers of materials built upon a first supportplate. One such layer may be a hydrophobic layer like a fluoropolymer(e.g., Teflon® AF1600®).

Hereinafter, example embodiments describe reflective electrowettingdisplays comprising an array of pixels sandwiched between a firstsupport plate and a second support plate. The first support plate may beopaque while the second support plate may be transparent. Herein,describing an element or material as being “transparent” means that theelement or material may transmit a relatively large fraction of thelight incident upon it. For example, a transparent substrate or layermay transmit more than 70% or 80% of the light impinging on its surface,though claimed subject matter is not limited in this respect.

The transparent second support plate may comprise glass or any of anumber of transparent materials, such as plastic, quartz,semiconductors, and so on, though claimed subject matter is not limitedin this respect. Also, as used herein for sake of convenience ofdescribing example embodiments, the second support plate is that throughwhich viewing of pixels of a (reflective) electrowetting display occurs.

Pixel walls retain at least a first fluid which is electricallynon-conductive and/or non-polar, such as opaque or colored oil, in theindividual pixels. A cavity formed between the support plates is filledwith the first fluid (e.g., the first fluid being retained by pixelwalls) and a second fluid (e.g., considered to be an electrolytesolution) that is polar and may or may not be electrically conductive,and may be a water solution, such as a mixture of water and ethylalcohol, or a salt solution, such as a solution of potassium chloride inwater. The second fluid may be transparent, but may be colored, orlight-absorbing. The second fluid is at least partially immiscible withthe first fluid.

In some embodiments, individual reflective electrowetting pixels mayinclude a reflective layer on the first support plate of theelectrowetting pixel, a transparent electrode layer adjacent to thereflective layer, and a hydrophobic layer on the electrode layer. Pixelwalls of each pixel, the hydrophobic layer, and the transparent secondsupport plate at least partially enclose a liquid region that includesan electrolyte solution and a light-absorbing or opaque liquid, which isimmiscible with the electrolyte solution. An “opaque” liquid, asdescribed herein, is used to describe a liquid that appears black orcolored to an observer. For example, a black opaque liquid stronglyabsorbs a broad spectrum of wavelengths (e.g., including those of red,green and blue) in the visible region of electromagnetic radiation. Insome implementations, the opaque liquid is a nonpolar oil.

The opaque liquid is disposed in the liquid region. As described indetail below, coverage area of the opaque liquid on the bottomhydrophobic layer is electronically adjustable to affect the amount oflight incident on the reflective electrowetting display that reaches thereflective material at the bottom of each pixel.

A spacer grid and edge seals which mechanically connect a first supportplate with a second overlying support plate, or which form a separationbetween the first support plate and the second support plate, contributeto mechanical integrity of the electrowetting display. Edge seals, forexample, being disposed along a periphery of an array of electrowettingdisplay device pixels, may contribute to retaining (e.g., first andsecond) fluids between the first support plate and the second overlyingsupport plate.

In some embodiments, a display device as described herein may comprise aportion of a system that includes one or more processors and one or morecomputer memories, which may reside on a control board, for example.Display software may be stored on the one or more memories and may beoperable with the one or more processors to modulate light that isreceived from an outside source (e.g., ambient light) or out-coupledfrom a light guide of the display device. For example, display softwaremay include code executable by a processor to modulate opticalproperties of individual pixels of the electrowetting display based, atleast in part, on electronic signals representative of image or videodata. The code may cause the processor to modulate the opticalproperties of pixels by controlling electrical signals (e.g., voltages,currents, fields, and so on) on, over, or in layers of theelectrowetting display.

FIG. 1 is a cross-section of a portion of a reflective electrowettingdisplay device illustrating several electrowetting pixels 100, accordingto some embodiments. Though three such electrowetting pixels areillustrated, an electrowetting display device may include any number(usually a very large number, such as thousands or millions) ofelectrowetting pixels. An electrode layer 102 is formed on a firstsupport plate 104 and may comprise one or more individual electrodes ineach electrowetting pixel.

In various embodiments, electrode layer 102 may be connected to anynumber of thin film transistors (TFTs) (not illustrated) that areswitched to either select or deselect electrowetting pixels 100 usingactive matrix addressing, for example. A TFT is a particular type offield-effect transistor that includes thin films of an activesemiconductor layer as well as a dielectric layer and metallic contactsover a supporting (but non-conducting) substrate, which may be glass orany of a number of other transparent or non-transparent materials, forexample.

In some implementations, a barrier layer 106 may at least partiallyseparate electrode layer 102 from a hydrophobic layer 108 also formed onfirst support plate 104. In some implementations, hydrophobic layer 108may comprise any of a number of types of fluoropolymers, such asAF1600®, produced by DuPont, based in Wilmington, Del. Hydrophobic layer108 may also be any of a number of water-repelling materials that affectwettability of an adjacent material, for example.

Pixel walls 110 form a patterned electrowetting pixel grid onhydrophobic layer 108. Pixel walls 110 may comprise a photoresistmaterial such as, for example, epoxy-based negative photoresist SU-8.The patterned electrowetting pixel grid comprises rows and columns thatform an array of electrowetting pixels. For example, an electrowettingpixel may have a width and length in a range of about 50 to 500 microns.In some implementations, the pixel walls need not be on the hydrophobiclayer. For example, pixel walls may be directly on the electrode layer(not illustrated in FIG. 1).

A first fluid 112, which may have a thickness (e.g., depth) in a rangeof about 1 to 10 microns, for example, overlies hydrophobic layer 108.First fluid 112 is partitioned by pixel walls 110 of the patternedelectrowetting pixel grid. An outer rim 114 may comprise the samematerial as pixel walls 110. A second fluid 116, such as an electrolytesolution, overlies first fluid 112 and pixel walls 110 of the patternedelectrowetting pixel grid. First fluid 112 is at least partiallyimmiscible with second fluid 116 so that the first fluid and the secondfluid do not substantially mix with each other, and in some examples donot mix with each other to any degree. Herein, substances are immisciblewith one another if the substances do not substantially form a solution.Second fluid 116 is preferably transparent, but may be colored orabsorbing. First fluid 112 is non-polar and may for instance be analkane like hexadecane or (silicone) oil.

A second support plate 118 covers second fluid 116 and edge seals 120maintain second fluid 116 over the electrowetting pixel array. Supportplate 118 may be supported by edge seals 120 and a spacer grid 122(various portions being illustrated as 122A and 122B) that maysubstantially extend over the array of pixels 100. As will be explainedbelow, some portions 122A of spacer grid 122 extend from tops 124 ofpixel walls 110 to second support plate 118 while other portions 122Bextend partially from tops 124 of pixel walls 110 to second supportplate 118, leaving a gap 126 (e.g., channel) herein called a “liquidduct”.

The reflective electrowetting display device has a viewing side 128 onwhich an image formed by the electrowetting display device may beviewed, and a rear side 130. Second support plate 118 faces viewing side128 and first support plate 104 faces rear side 130. The electrowettingdisplay device may be an active matrix driven display type or a passivematrix driven display, just to name a few examples.

Separation block 132 represents a discontinuity of electricalconductivity along electrode layer 102. For example, a first portion 134of electrode layer 102 may be electrically insulated or separated from asecond portion 136 and a third portion 138 of electrode layer 102 sothat each portion 134, 136, and 138 is connected to a respective pixelregion.

In some embodiments, electrowetting pixels may include a top electrode140 disposed on second support plate 118, one or more color filters (notillustrated), or a black matric (not illustrated). The electrode on thesecond support plate may or may not be patterned to form any of a numberof circuit configurations, for example.

Hydrophobic layer 108 is arranged on first support plate 104 to createan electrowetting surface area. The hydrophobic character causes firstfluid 112 to adhere preferentially to first support plate 104 sincefirst fluid 112 has a higher wettability with respect to the surface ofhydrophobic layer 108 than second fluid 116. Wettability relates to therelative affinity of a fluid for the surface of a solid. Wettabilityincreases with increasing affinity, and it may be measured by thecontact angle formed between the fluid and the solid and measuredinternal to the fluid of interest. For example, such a contact angle mayincrease from relative non-wettability of more than 90° to completewettability at 0°, in which case the fluid tends to form a film on thesurface of the solid.

First fluid 112 absorbs at least a part of the optical spectrum. Firstfluid 112 may be transmissive for a part of the optical spectrum,forming a color filter. For this purpose, the fluid may be colored byaddition of pigment particles or dye, for example. Alternatively, firstfluid 112 may be colored or black (e.g., absorbing substantially allparts of the optical spectrum) or reflecting. Hydrophobic layer 108 maybe transparent or reflective. A reflective layer may reflect the entirevisible spectrum, making the layer appear white, or part of it, makingit have a color.

If a voltage is applied across electrowetting pixel 100 (e.g., betweenelectrode layer 102 and top electrode 140), electrowetting pixel 100will enter into an active state. Electrostatic forces will move secondfluid 116 toward electrode layer 102, thereby displacing first fluid 112from the area of hydrophobic layer 108 to pixel walls 110 surroundingthe area of hydrophobic layer 108, to a droplet-like shape. Suchdisplacing action uncovers first fluid 112 from the surface ofhydrophobic layer 108 of electrowetting pixel 100.

If the voltage across electrowetting pixel 100 is returned to aninactive signal level of zero or a value near to zero, electrowettingpixel 100 will return to an inactive state, where first fluid 112 flowsback to cover hydrophobic layer 108. In this way, first fluid 112 formsan electrically controllable optical switch in each electrowetting pixel100. Of course, such details of an electrowetting display device aremerely examples, and claimed subject matter is not limited in thisrespect.

FIG. 2 is a perspective view of a portion of a spacer grid 200 that maybe incorporated in an electrowetting display, according to variousembodiments. Though not illustrated, a bottom surface 202 of spacer grid200 may be joined to tops of pixel walls. Though figures hereinillustrate pixel regions that are rectangular or square, pixel regionsneed not have such shapes. For example pixel regions may be round, oval,or have five or more sides, and claimed subject matter is not limited inthis respect.

Spacer grid 200 includes liquid ducts 204 that may be distributed alongtops of rows 206 and/or columns 208 of spacer grid 200. As will bediscussed below, liquid ducts may have any of a number of shapes, suchas a rectangular shape illustrated in FIG. 2. In this case, liquid ducts204 include a sidewall 210 and a bottom portion 212. Apertures 214,which may coincide with pixel regions, are situated among the rows andcolumns of spacer grid 200. In some implementations, spacer grid 200 maycomprise a material that is hydrophilic to an electrolyte solution. Inother words, spacer grid 200 may have an affinity for the electrolytesolution but not for oil. In some implementations, material for spacergrid 200 may include one or more different types of materials. Forexample, spacer grid 200 may comprise a multilayer construction thatincludes one or more different types of materials, which may include oneor more different types of photoresist materials.

Though not illustrated in FIG. 2, in some implementations, top surfaces216 may be joined to a second support plate of an electrowetting displayby an adhesive, for example. In other implementations, top surfaces 216may be formed (e.g., fabricated) on a second support plate.

FIG. 3 is a top view of a portion 300 of an electrowetting displaydevice, illustrating a spacer grid 302, according to variousembodiments. Among other things, pixel walls (not illustrated in FIG. 3)and spacer grid 302 may be disposed on a first support plate portion304. For sake of clarity, various layer and elements (e.g., electrodelayers, a hydrophobic layer, and barrier layers) that may be disposed onfirst support plate portion 304 are not illustrated. Also for sake ofclarity, spacer grids herein are illustrated as aligning with pixelwalls so that portions of the spacer grid are disposed on pixel walls inevery pixel region. This, however, need not be the case. For example, agrid structure of a spacer grid may be coarser (e.g., lower density ofapertures per unit area) as compared to a grid of pixel walls on whichthe spacer grid is disposed. Claimed subject matter is not limited inthis respect. The pixel walls may be disposed on a hydrophobic layer(not illustrated in FIG. 3) and partition pixel regions 306 from oneanother. Spacer grid 302 may be disposed on tops of the pixel walls.Though not illustrated, pixel regions may be filled with an oil and anelectrolyte solution may be disposed over at least portions of thehydrophobic layer, the pixel walls, the oil, and may surround spacergrid 302. A second support plate, such as second support plate 118illustrated in FIG. 1, may cover portion 300 and enclose the electrolytesolution and the oil, for example.

Spacer grid 302 may include a plurality of liquid ducts along columns308 and rows 310 of spacer grid 302. In particular, for example, liquidducts 312 may be positioned along columns 308 and liquid ducts 314 maybe positioned along rows 310. Liquid ducts situated in rows may be thesame as or different from liquid ducts situated in columns. Liquid ductssituated in rows may be the same or different along the rows, and liquidducts situated in columns may be the same or different along thecolumns. Also combinations of similar liquid ducts situated in rows withliquid ducts situated in columns having variable shapes and dimensionsor combinations of similar liquid ducts situated in columns with liquidducts in rows having variable shapes and dimensions are possible. Thelocation of the liquid ducts can also differ within rows and columns.Liquid ducts may include a sidewall 316 and a bottom surface 318, eitherof which may be orthogonal to one another or angled, based, at least inpart, on the shape of the liquid ducts.

In some embodiments, a liquid duct may be included in each section ofspacer grid 302 that surrounds each pixel region 306, as shown in FIG.3. In other embodiments, a liquid duct may be included in alternate (orother combination or pattern of) sections of spacer grid 302 thatsurrounds each pixel region 306. In still other embodiments, more thanone liquid duct may be included in each section of spacer grid 302 thatsurrounds each pixel region 306.

A section line A-A′ is drawn through a row 310 of spacer grid 302. Asection line B-B′ is drawn through portions of spacer grid 302 andapertures 306. A section line C-C′ is drawn through apertures 306 andportions of spacer grid 302 that include liquid ducts. These sectionlines are described below.

FIG. 4 includes a cross-sectional view of a portion of spacer grid 302along section line A-A′, according to various embodiments. Spacer grid302 is disposed on pixel wall 402, which is disposed on first supportplate portion 304. Though spacer grid 302 may be joined (e.g., via anadhesive) to pixel wall 402, in some embodiments, spacer grid 302 may beformed on and include a second support plate (not shown in FIG. 4). Forexample, a structure that includes spacer grid 302 and a second supportplate may be joined to tops of pixel walls during a fabrication processthat laminates or otherwise joins the spacer grid/second support platestructure with a first support plate structure that includes the pixelwalls. Widths of portions of spacer grid 302 may be the same as ordifferent from pixel wall 402, and claimed subject matter is not limitedin this respect.

Spacer grid 302 may include liquid ducts 314 having side walls 316 andbottom surfaces 318. A top surface 404 may be in contact (e.g., disposedon) the second support plate. Dashed vertical lines 406 indicatelocations of centers of columns of spacer grid 302 and pixel wall 402. Atop support plate 408 is adjacent to spacer grid 302 and borders oneside of the liquid ducts.

FIG. 5 includes a cross-sectional view of a portion of spacer grid 302along section line B-B′, according to various embodiments. Spacer grid302 is disposed on pixel wall 402, which is disposed on first supportplate portion 304. Liquid ducts are not included in section line B-B′.Accordingly, second support plate 408 is in contact with spacer grid inthis illustration. Columns of spacer grid 302 and columns of pixel wall402 partition pixel regions 306.

FIG. 6 is a cross-sectional view of a portion of spacer grid 302 alongsection line C-C′, according to various embodiments. Spacer grid 302 isdisposed on pixel wall 402, which is disposed on first support plateportion 304. Liquid ducts are disposed on top portions 602 of spacergrid 302 along section line C-C′. Top portions 602 coincide with bottomsurfaces 318 (illustrated in FIG. 3) of liquid ducts 314. In thecross-section, presence of liquid ducts is apparent by the gap 604 ontop portions 602. Gap 604 is between top portions 602 and second supportplate 408.

FIGS. 7-9 are cross-sectional views of a portion of a spacer grid,illustrating various shapes and sizes (e.g., width and height) of liquidducts, according to embodiments. For example, such cross-sections may bealong section line A-A′ illustrated in FIG. 3. In some examples, depthsof liquid ducts in a spacer grid may be about one-third the height ofthe spacer grid, though claimed subject matter is not limited in thisrespect. In some implementations, depths and other dimensions of liquidducts may vary randomly or by location across the array of pixel regionson which the spacer grid is disposed.

In FIG. 7, a spacer grid 702 is disposed on a pixel wall 704, which isdisposed on a first support plate portion 706. Spacer grid 702 mayinclude liquid ducts 708 having sloped side walls 710. A top surface 712may be in contact (e.g., disposed on) a second support plate. Dashedvertical lines 714 indicate locations of centers of intersecting columnsof spacer grid 702 and pixel wall 704. Top support plate 716 borders oneside of liquid ducts 708.

In FIG. 8, a spacer grid 802 is disposed on a pixel wall 804, which isdisposed on a first support plate portion 806. Spacer grid 802 mayinclude liquid ducts 808 having sloped side walls 810. A top surface 812may be in contact (e.g., disposed on) a second support plate. Dashedvertical lines 814 indicate locations of centers of intersecting columnsof spacer grid 802 and pixel wall 804. Top support plate 816 borders oneside of liquid ducts 808.

In FIG. 9, a spacer grid 902 is disposed on a pixel wall 904, which isdisposed on a first support plate portion 906. Spacer grid 902 mayinclude liquid ducts 908 and portions 910 (indicated by dashedrectangle) of spacer grid 902 between the liquid ducts and a top surface912. In other words, such liquid ducts are not in contact with topsurface 912. A second support plate may be in contact with top surface912. Dashed vertical lines 914 indicate locations of centers ofintersecting columns of spacer grid 902 and pixel wall 904. Top supportplate 916 borders adjacent surface 912.

FIG. 10 is a cross-sectional view of a portion of an electrowettingdisplay that includes a bottom structure 1000, a spacer grid 1002disposed on pixel walls 1004, and a second support plate 1006, accordingto various embodiments. For sake of clarity, elements and layers on afirst support plate below the bottom of oil 1008, and the first supportplate itself, are not illustrated in FIG. 10. A surface 1010 maycomprise a top of a hydrophobic layer, for example. Second support plate1006 covers bottom structure 1000. In some embodiments, spacer grid 1002may be formed on top plate 1006, while in other embodiments spacer grid1002 may be formed on pixel walls 1004. Gaps 1012 indicate the presenceof liquid ducts between second support plate 1006 and spacer grid 1002in this particular cross-section. In the example embodiment, portions1013 of spacer grid 1002 are illustrated as being in contact with secondsupport plate 1006. Thus, for example, locations of liquid ducts mayvary over different parts of spacer grid 1002.

Spacer grid 1002 incorporated in an electrowetting display contributesto the mechanical integrity of the electrowetting display. Inparticular, a spacer grid may provide a relatively large amount ofsurface area of a second support plate that is mechanically supported bythe spacer grid. Also, spacer grid 1002 may add effective height topixel walls 1004 and thus reduce likelihood of “spill-over”, describedin detail below.

Spacer grid 1002 joined to tops of pixel walls 1004 add to the height ofthe pixel walls disposed on the first support plate. The resulting extrawall height may help prevent oil from “spilling” over pixel walls fromone pixel region to an adjacent pixel region. Such spilling may occur,for example, due to mechanical shock that tends to produce a surge orother such movement of oil 1008. Likelihood of spill-over by surging maybe greater for an active pixel, such as active pixel region 1014A. Fourpixel regions are illustrated in the figure, of which one pixel region1014A is active and three pixels regions 1014B-1014D are inactive.

In active pixel region 1014A, a portion 1016 of oil may be displaced“tightly” against pixel walls 1004 and spacer grid 1002 toward an edgeof the pixel region. Because forces inducing such displacement areprimarily in a horizontal (e.g. parallel with the support plates)direction, the displaced oil tends to be squeezed in an upward directionalong the pixel walls resulting in a relatively tall bead of oil portion1016. This may be compared to oil 1008 in an inactive pixel region1014B, for example. Top portions of such a tall bead of oil may spillover the pixel walls without a spacer grid, a scenario of which isindicated by arrow 1018. Spacer grid 1002 effectively increases theoverall height of the pixel “walls” and thus may prevent such spillover.For example, arrow 1020 indicates the extra height (by the presence ofspacer grid 1002) that oil would need to surpass to surge to an adjacentpixel region.

In some embodiments, an electrolyte solution 1022 covers oil 1008,spacer grid 1002, and pixel walls 1004. During a fabrication process,the first support plate including the pixel walls is laminated orotherwise coupled to top plate 1006 that includes the spacer grid by arolling process, for example. During such a process, excess electrolytesolution 1022 may be squeezed out from between bottom portion 1000 andtop plate 1006. Flow of excess electrolyte solution 1022 duringfabrication is indicated by arrow 1024, which occurs through gaps (e.g.,liquid ducts) 1012. For at least the reason that liquid ducts aresituated relatively high above oil 1008, a tendency of flowing excesselectrolyte solution to disturb oil 1008 may be reduced.

FIG. 11 is a top view of a portion 1100 of an electrowetting displaydevice, illustrating a spacer grid 1102, according to variousembodiments. Portion 1100 is similar to portion 300, illustrated in FIG.3, except that liquid ducts 1104 are not situated at centers of sides ofpixel regions 1106 as they are for portion 300. Instead, liquid ducts1104 may be situated toward corners of pixel regions 1106. In otherwords, liquid ducts 1104 need not be situated at any particular portionof spacer grid 1102. In some embodiments, a liquid duct may be includedin each section of spacer grid 1102 that surrounds each pixel region1106. In other embodiments, a liquid duct may be included in alternate(or other combination or pattern of) sections of spacer grid 1102 thatsurrounds each pixel region 1106. In still other embodiments, more thanone liquid duct may be included in each section of spacer grid 1102 thatsurrounds each pixel region 1106.

FIG. 12 is a perspective view of the portion of a spacer grid 1200,which may be similar to or the same as spacer grid 200, previouslyillustrated in FIG. 2, according to various embodiments. Dashed line1202 indicates an interface between materials deposited during differentprocess of fabrication. For example, in one embodiment, “X”-structures1204 (above dashed line 1202) that separate liquid ducts 1206 may beformed in a process separate from forming grid portion 1208 (belowdashed line 1202). Liquid ducts 1206 may be considered to be channels in“X”-structures 1204. Moreover, portions of grid portion 1208 includebridges 1210 that span across the channels (though such “bridges” aredepicted in an “upside-down” fashion in FIG. 12). In some embodiments,spacer grid 1200 may include a first material (X-structures 1204) abovedashed line 1202 and a second material (grid portion 1208) differentfrom the first material below dashed line 1202.

FIGS. 13-16 illustrate portions of a process for fabricating a spacergrid, such as spacer grid 200, for example, which includes liquid ducts.FIGS. 13-16 are cross-sectional views that may be along, for example, aline section C-C′, illustrated in FIG. 3.

In FIG. 13, a first spacer material 1302 may be deposited on a secondsupport plate 1304, which may comprise glass, plastic, or othertransparent material. Techniques for depositing first spacer material1302 may include, for example, wet coating techniques like, for example,spin coating or slit coating. First spacer material 1302 may comprise,for example, a photoresist material, plastic, or an epoxy material, justto name a few examples. In some cases, a spacer material may comprise anepoxy-based negative photoresist SU-8. First spacer material 1302 may bedeposited to a thickness of D, which may be the depth of the liquidducts that will be formed from the first spacer material. An etch mask1306 may be placed on or over a surface of first spacer material 1302.Such an etch mask may be used for photolithography processes, forexample. In some implementations, an etch mask may be a separate part,for example, in an exposure machine and need not be physically addedand/or attached to any layer or portion (e.g., sacrificial layer orphotoresist layer) of the spacer grid. Regions of first spacer material1302 not covered by etch mask 1306 may be exposed to electromagnetic(EM) radiation, which may change the physical properties of first spacermaterial 1302. For example, portions of first spacer material 1302exposed to EM radiation may be etched or dissolved by a subsequentprocess, whereas portions of first spacer material 1302 not exposed tothe EM radiation may be resistant to etching or dissolution by thesubsequent process. In some implementations, etch mask 1306 may comprisea black photo-sensitive material having substantially zero light or EMtransmission.

FIG. 14 illustrates portions 1402 of first spacer material 1302 exposedto EM radiation and portions 1404 of first spacer material 1302 notexposed to the EM radiation. Accordingly, as explained above, portions1402 may be etched or dissolved by a particular process, whereasportions 1404 may be resistant to etching or dissolution by theparticular process.

In FIG. 15, a second spacer material 1502 may be deposited on spacermaterial 1302 and etch mask 1306. Etching mask 1306 may be removed ormay remain and be of use in subsequent processing steps. Such materialmay comprise, for example, a photoresist material, plastic, or an epoxymaterial, just to name a few examples. Techniques for depositing secondspacer material 1502 may include, for example, spincoating, slitcoating,or lamination. In some implementations, a thickness of first spacermaterial 1302 is less than a thickness of second spacer material 1502.Second spacer material 1502 may be deposited to a thickness of d, whichmay be the height of a top portion of a spacer grid that will be formedfrom the second spacer material. An etch mask 1504 may be placed on asurface of second spacer material 1502. Such an etch mask may be usedfor photolithography processes, for example. Regions of second spacermaterial 1502 not covered by etch mask 1504 may be exposed to EMradiation, which may change the physical properties of second spacermaterial 1502. For example, portions of second spacer material 1502exposed to EM radiation may be etched or dissolved by a particularprocess, whereas portions of second spacer material 1502 not exposed tothe EM radiation may be resistant to etching or dissolution by theparticular process (positive imaging).

FIG. 16 illustrates a cross-sectional view of a portion of the structurein FIG. 15 subsequent to an etching process where both first spacermaterial 1302 and second spacer material 1502 are etched to the surfaceof second support plate 1304 between non-exposed first spacer material1404. Such an etching process may be a single etching process thatetches and removes both the first spacer material and the second spacermaterial. During the etching process, the exposed first spacer material1302 is etched away, leaving non-exposed first spacer material 1404 toremain and form bottom spacer portions 1602. Top spacer portion 1604 maycomprise walls of a spacer grid. Etch mask 1504 may be removed, thoughetch mask 1306 (which may comprise a black matrix) may remain. Liquidducts may be included in bottom spacer portions 1602, wherein theetching process under-etches between top spacer portion 1604 and secondsupport plate 1304. Top spacer portion 1604 includes self-supporting“bridges” spanning across channels that are liquid ducts. Such bridgesare not visible in the cross-section view of FIG. 16. The perspectiveview of FIG. 12, however, illustrates such bridges (e.g., bridges 1210).Apertures 1606 coincide with pixel regions that are formed after thestructure illustrated in FIG. 16 is joined with a first support platehaving pixel walls disposed thereon.

FIGS. 17-21 illustrate portions of a process for fabricating a spacergrid, such as spacer grid 200, for example, which includes liquid ducts.FIGS. 17-21 are cross-sectional views that may be along, for example, aline section C-C′, illustrated in FIG. 3. In FIG. 17, a sacrificiallayer 1702 may be deposited on a transparent support plate 1704.Sacrificial material may comprise any of a number of materials, such asa photoresist, for example. In some implementations, transparent supportplate 1704 may include a substrate and an electrode layer, for example.Techniques for depositing sacrificial layer 1702 may include, forexample, spin coating, slit coating, or lamination. Sacrificial layer1702 may be deposited to a thickness of D, which may be the depth ofliquid ducts that will be formed from the sacrificial layer. A firstmask 1706 may be placed on sacrificial layer 1702. Portions ofsacrificial layer 1702 not covered by first mask 1706 may be exposed toEM radiation

In FIG. 18, exposed portions of sacrificial layer 1702 may subsequentlybe etched and removed so that the mask-covered portions of sacrificiallayer 1702 remain on transparent support plate 1704. The remainingportions of sacrificial layer 1702 are called “liquid duct forms”because they will subsequently be used as temporary structural formsthat displace a photoresist material to create cavities that are liquidducts, as described below. For example, a liquid duct form prevents thephotoresist material from occupying the space of the liquid duct form. Acavity in the photoresist material will be created by the subsequentremoval of the liquid duct form. Accordingly, liquid duct forms 1802 areillustrated in FIG. 18. In some implementations, liquid duct forms maybe made from a dissolvable material using a transfer grid material, forexample. In such cases, an embossed material may be used.

In FIG. 19, a photoresist layer 1902 may be deposited on liquid ductforms 1802 and transparent support plate 1704, though in someimplementations layer 1902 need not be a photoresist material. Liquidduct forms 1802 extend outward from transparent support plate 1704 to afirst distance. Photoresist layer 1902 may be deposited beyond the firstdistance to a thickness of d, indicated in FIG. 19, which may be theheight of spacer walls bridging liquid ducts. A mask 1904 may bedeposited on the photoresist layer. For example, mask 1904 may includerows and columns that form a grid. Portions of photoresist layer 1902not covered by mask 1904 may be exposed to EM energy.

In FIG. 20, exposed portions of photoresist layer 1902 may subsequentlybe etched and removed so that the mask-covered portions of photoresistlayer 1902 remain on liquid duct forms 1802 to form a spacer gridportion 2002. Mask 1904 may be removed. Next, an etch process removesliquid duct forms 1802, which may be made from a sacrificial material.For example the sacrificial material may be etched with an etch processthat does not substantially affect spacer grid portion 2002. Such anetch process may remove material of liquid duct forms 1802 throughapertures 2004. For example, spacer walls of grid portion 2002 maypartition apertures 2004 from one another. A resulting structure isillustrated in FIG. 21. Dashed rectangles indicate liquid ducts 2102disposed between transparent support plate 1704 and spacer grid portion2002. Though not visible in FIG. 21, regions where etched photoresistlayer 1902 is in contact with transparent support plate 1704 may havecross or “X” shapes for example, or any other shape.

In some embodiments, a process for etching or otherwise removing (e.g.,by dissolving) liquid duct forms 1802 may be varied depending, at leastin part, on location with respect to transparent support plate 1704.Such variation may allow for varying the size of liquid ducts formed bythe etching or removing process. For example, duration of an etchingprocess for liquid duct forms 1802 located in one portion of transparentsupport plate 1704 may be longer compared to duration of the etchingprocess in another portion of transparent support plate 1704. Ingeneral, a longer etching process may result in larger liquid ducts byremoving more material from liquid duct forms 1802.

FIG. 22 is a flow diagram of a process 2200 for fabricating a spacergrid, according to various example embodiments. For example, process2200 may be similar to or the same as fabrication processes depicted inFIGS. 17-21. At block 2202, a sacrificial layer may be deposited on asupport plate, which may be transparent. In some implementations, thetransparent support plate may include a substrate and an electrodelayer, for example. Techniques for depositing the sacrificial layer mayinclude, for example, spincoating, slitcoating, or lamination. Thesacrificial layer may be deposited to a particular thickness that may bethe depth of liquid ducts that will be formed from the sacrificiallayer. A first mask may be placed on the sacrificial layer. Portions ofthe sacrificial layer not covered by the first mask may be exposed to EMenergy.

At block 2204, portions of the sacrificial layer may subsequently beetched and removed so that the mask-covered portions of the sacrificiallayer remain on the transparent support plate. The remaining portions ofthe sacrificial layer are liquid duct forms.

At block 2206, a photoresist layer may be deposited on the liquid ductforms and the transparent support plate. The photoresist layer may bedeposited to a particular thickness, which may be the height of spacerwalls bridging liquid ducts. A second mask may be placed on thephotoresist layer. For example, the second mask may include rows andcolumns that form a grid. Portions of the photoresist layer not coveredby the second mask may be exposed to EM radiation

At block 2208, exposed portions of the photoresist layer maysubsequently be etched and removed so that the mask-covered portions ofthe photoresist layer remain on the liquid duct forms to form a spacergrid portion. The second mask may be removed. At block 2210, an etchingor dissolving process removes the liquid duct forms, which are made froma sacrificial material that may be removed with an etch process thatdoes not substantially affect the spacer grid portion.

In one embodiment, returning to block 2206, the photoresist layerdeposited on the liquid duct forms and the transparent support plate maybe covered with a black etch mask. By not removing this black etch maskafter fabrication of the spacer grid structure, this black etch mask mayact as a black matrix. In other words, the second mask deposited on thephotoresist layer may be a black matrix. For example, the black matrixmay include rows and columns that form a grid. The black matrix mayremain in the spacer grid structure, even after fabrication iscompleted. The black matrix may provide a number of benefits by beinglocated relatively close to the bottom (e.g., the oil, electrodeportion) of a pixel region. For example, the black matrix, providing alight absorbing screen, may improve optical performance by reducingoptical crosstalk between and among the pixel regions.

FIG. 23 illustrates an example electronic device 2300 that mayincorporate any of the display devices discussed above. The device 2300may comprise any type of electronic device having a display. Forinstance, the device 2300 may be a mobile electronic device (e.g., anelectronic book reader, a tablet computing device, a laptop computer, asmart phone or other multifunction communication device, a portabledigital assistant, a wearable computing device, an automotive display,etc.). Alternatively, the device 2300 may be a non-mobile electronicdevice (e.g., a computer display, a television, etc.). In addition,while FIG. 23 illustrates several example components of the electronicdevice 2300, it is to be appreciated that the device 2300 may alsoinclude other conventional components, such as an operating system,system busses, input/output components, and the like. Further, in otherexamples, such as in the case of a television or computer monitor, theelectronic device 2300 may only include a subset of the componentsillustrated.

Regardless of the specific implementation of the electronic device 2300,the device 2300 includes a display 2302 and a corresponding displaycontroller 2304. The display 2302 may represent a reflective ortransmissive display.

In an implementation, the display comprises an electrowetting displaythat employs an applied voltage to change the surface tension of a fluidin relation to a surface. For example, such an electrowetting displaymay include the array of pixels 100 illustrated in FIG. 1, thoughclaimed subject matter is not limited in this respect. By applying avoltage across a portion of an electrowetting pixel of an electrowettingdisplay, wetting properties of a surface may be modified so that thesurface becomes increasingly hydrophilic. As one example of anelectrowetting display, the modification of the surface tension acts asan optical switch by contracting a colored oil film if a voltage isapplied to individual pixels of the display. If the voltage is absent,the colored oil forms a continuous film within a pixel, and the colormay thus be visible to a user of the display. On the other hand, if thevoltage is applied to the pixel, the colored oil is displaced and thepixel becomes transparent. If multiple pixels of the display areindependently activated, the display may present a color or grayscaleimage. The pixels may form the basis for a transmissive, reflective, ortransmissive/reflective (transreflective) display. Further, the pixelsmay be responsive to high switching speeds (e.g., on the order ofseveral milliseconds), while employing small pixel dimensions.Accordingly, the electrowetting displays herein may be suitable forapplications such as displaying video content.

Of course, while several different examples have been given, it is to beappreciated that while some of the examples described above arediscussed as rendering black, white, and varying shades of gray, it isto be appreciated that the described techniques apply equally toreflective displays capable of rendering color pixels. As such, theterms “white,” “gray,” and “black” may refer to varying degrees of colorin implementations utilizing color displays. For instance, where a pixelincludes a red color filter, a “gray” value of the pixel may correspondto a shade of pink while a “black” value of the pixel may correspond toa darkest red of the color filter. Furthermore, while some examplesherein are described in the environment of a reflective display, inother examples, the display 2302 may represent a backlit display,examples of which are mentioned above.

In addition to including the display 2302, FIG. 23 illustrates that someexamples of the device 2300 may include a touch sensor component 2306and a touch controller 2308. In some instances, at least one touchsensor component 2306 resides with, or is stacked on, the display 2302to form a touch-sensitive display. Thus, the display 2302 may be capableof both accepting user touch input and rendering content in response toor corresponding to the touch input. As several examples, the touchsensor component 2306 may comprise a capacitive touch sensor, a forcesensitive resistance (FSR), an interpolating force sensitive resistance(IFSR) sensor, or any other type of touch sensor. In some instances, thetouch sensor component 2306 is capable of detecting touches as well asdetermining an amount of pressure or force of these touches.

FIG. 23 further illustrates that the electronic device 2300 may includeone or more processors 2310 and one or more computer-readable media2312, as well as a front light component 2314 (which may alternativelybe a backlight component in the case of a backlit display) for lightingthe display 2302, a cover layer component 2316, such as a cover glass orcover sheet, one or more communication interfaces 2318 and one or morepower sources 2320. The communication interfaces 2318 may support bothwired and wireless connection to various networks, such as cellularnetworks, radio, WiFi networks, short range networks (e.g., Bluetooth®),infrared (IR), and so forth.

Depending on the configuration of the electronic device 2300, thecomputer-readable media 2312 (and other computer-readable mediadescribed throughout) is an example of computer storage media and mayinclude volatile and nonvolatile memory. Thus, the computer-readablemedia 2312 may include, but is not limited to, RAM, ROM, EEPROM, flashmemory, or other memory technology, or any other medium that may be usedto store computer-readable instructions, programs, applications, mediaitems, and/or data which may be accessed by the electronic device 2300.

The computer-readable media 2312 may be used to store any number offunctional components that are executable on the processor 2310, as wellas content items 2322 and applications 2324. Thus, the computer-readablemedia 2312 may include an operating system and a storage database tostore one or more content items 2322, such as eBooks, audio books,songs, videos, still images, and the like. The computer-readable media2312 of the electronic device 2300 may also store one or more contentpresentation applications to render content items on the device 2300.These content presentation applications may be implemented as variousapplications 2324 depending upon the content items 2322. For instance,the content presentation application may be an electronic book readerapplication for rending textual electronic books, an audio player forplaying audio books or songs, a video player for playing video, and soforth.

In some instances, the electronic device 2300 may couple to a cover (notillustrated in FIG. 23) to protect the display (and other components inthe display stack or display assembly) of the device 2300. In oneexample, the cover may include a back flap that covers a back portion ofthe device 2300 and a front flap that covers the display 2302 and theother components in the stack. The device 2300 and/or the cover mayinclude a sensor (e.g., a Hall Effect sensor) to detect if the cover isopen (i.e., if the front flap is not atop the display and othercomponents). The sensor may send a signal to the front light component2314 if the cover is open and, in response, the front light component2314 may illuminate the display 2302. If the cover is closed, meanwhile,the front light component 2314 may receive a signal indicating that thecover has closed and, in response, the front light component 2314 mayturn off.

Furthermore, the amount of light emitted by the front light component2314 may vary. For instance, upon a user opening the cover, the lightfrom the front light may gradually increase to its full illumination. Insome instances, the device 2300 includes an ambient light sensor (notillustrated in FIG. 23) and the amount of illumination of the frontlight component 2314 may be based at least in part on the amount ofambient light detected by the ambient light sensor. For example, thefront light component 2314 may be dimmer if the ambient light sensordetects relatively little ambient light, such as in a dark room; may bebrighter if the ambient light sensor detects ambient light within aparticular range; and may be dimmer or turned off if the ambient lightsensor detects a relatively large amount of ambient light, such asdirect sunlight.

In addition, the settings of the display 2302 may vary depending onwhether the front light component 2314 is on or off, or based on theamount of light provided by the front light component 2314. Forinstance, the electronic device 2300 may implement a larger default fontor a greater contrast if the light is off compared to if the light ison. In some instances, the electronic device 2300 maintains, if thelight is on, a contrast ratio for the display that is within a certaindefined percentage of the contrast ratio if the light is off.

As described above, the touch sensor component 2306 may comprise acapacitive touch sensor that resides atop the display 2302. In someexamples, the touch sensor component 2306 may be formed on or integratedwith the cover layer component 2316. In other examples, the touch sensorcomponent 2306 may be a separate component in the stack of the displayassembly. The front light component 2314 may reside atop or below thetouch sensor component 2306. In some instances, either the touch sensorcomponent 2306 or the front light component 2314 is coupled to a topsurface of a protective sheet 2326 of the display 2302. As one example,the front light component 2314 may include a lightguide sheet and alight source (not illustrated in FIG. 23). The lightguide sheet maycomprise a substrate (e.g., a transparent thermoplastic such as PMMA orother acrylic), a layer of lacquer and multiple grating elements formedin the layer of lacquer that function to propagate light from the lightsource towards the display 2302, thus illuminating the display 2302.

The cover layer component 2316 may include a transparent substrate orsheet having an outer layer that functions to reduce at least one ofglare or reflection of ambient light incident on the electronic device2300. In some instances, the cover layer component 2316 may comprise ahard-coated polyester and/or polycarbonate film, including a basepolyester or a polycarbonate, that results in a chemically bondedUV-cured hard surface coating that is scratch resistant. In someinstances, the film may be manufactured with additives such that theresulting film includes a hardness rating that is greater than apredefined threshold (e.g., at least a hardness rating that is resistantto a 3 h pencil). Without such scratch resistance, a device may be moreeasily scratched and a user may perceive the scratches from the lightthat is dispersed over the top of the reflective display. In someexamples, the protective sheet 2326 may include a similar UV-cured hardcoating on the outer surface. The cover layer component 2316 may coupleto another component or to the protective sheet 2326 of the display2302. The cover layer component 2316 may, in some instances, alsoinclude a UV filter, a UV-absorbing dye, or the like, for protectingcomponents lower in the stack from UV light incident on the electronicdevice 2300. In still other examples, the cover layer component 2316 mayinclude a sheet of high-strength glass having an antiglare and/orantireflective coating.

The display 2302 includes the protective sheet 2326 overlying animage-displaying component 2328. For example, the display 2302 may bepreassembled to have the protective sheet 2326 as an outer surface onthe upper or image-viewing side of the display 2302. Accordingly, theprotective sheet 2326 may be integral with and may overlie theimage-displaying component 2328. The protective sheet 2326 may beoptically transparent to enable a user to view, through the protectivesheet 2326, an image presented on the image-displaying component 2328 ofthe display 2302.

In some examples, the protective sheet 2326 may be a transparent polymerfilm in the range of 25 to 200 micrometers in thickness. As severalexamples, the protective sheet may be a transparent polyester, such aspolyethylene terephthalate (PET) or polyethylene naphthalate (PEN), orother suitable transparent polymer film or sheet, such as apolycarbonate or an acrylic. In some examples, the outer surface of theprotective sheet 2326 may include a coating, such as the hard coatingdescribed above. For instance, the hard coating may be applied to theouter surface of the protective sheet 2326 before or after assembly ofthe protective sheet 2326 with the image-displaying component 2328 ofthe display 2302. In some examples, the hard coating may include aphotoinitiator or other reactive species in its composition, such as forcuring the hard coating on the protective sheet 2326. Furthermore, insome examples, the protective sheet 2326 may be dyed with aUV-light-absorbing dye, or may be treated with other UV-absorbingtreatment. For example, the protective sheet may be treated to have aspecified UV cutoff such that UV light below a cutoff or thresholdwavelength is at least partially absorbed by the protective sheet 2326,thereby protecting the image-displaying component 2328 from UV light.

According to some implementations herein, one or more of the componentsdiscussed above may be coupled to the display 2302 using fluidoptically-clear adhesive (LOCA). For example, suppose that the lightguide portion of the front light component 2314 is to be coupled to thedisplay 2302. The light guide may be coupled to the display 2302 byplacing the LOCA on the outer or upper surface of the protective sheet2326. If the LOCA reaches the corner(s) and/or at least a portion of theperimeter of protective sheet, UV-curing may be performed on the LOCA atthe corners and/or the portion of the perimeter. Thereafter, theremaining LOCA may be UV-cured and the front light component 2314 may becoupled to the LOCA. By first curing the corner(s) and/or perimeter, thetechniques effectively create a barrier for the remaining LOCA and alsoprevent the formation of air gaps in the LOCA layer, thereby increasingthe efficacy of the front light component 2314. In otherimplementations, the LOCA may be placed near a center of the protectivesheet 2326, and pressed outwards towards a perimeter of the top surfaceof the protective sheet 2326 by placing the front light component 2314on top of the LOCA. The LOCA may then be cured by directing UV lightthrough the front light component 2314. As discussed above, and asdiscussed additionally below, various techniques, such as surfacetreatment of the protective sheet, may be used to prevent discolorationof the LOCA and/or the protective sheet 2326.

While FIG. 23 illustrates a few example components, the electronicdevice 2300 may have additional features or functionality. For example,the device 2300 may also include additional data storage devices(removable and/or non-removable) such as, for example, magnetic disks,optical disks, or tape. The additional data storage media, which mayreside in a control board, may include volatile and nonvolatile,removable and non-removable media implemented in any method ortechnology for storage of information, such as computer readableinstructions, data structures, program modules, or other data. Inaddition, some or all of the functionality described as residing withinthe device 2300 may reside remotely from the device 2300 in someimplementations. In these implementations, the device 2300 may utilizethe communication interfaces 2318 to communicate with and utilize thisfunctionality.

Although the subject matter has been described in language specific tostructural features and/or methodological acts, it is to be understoodthat the subject matter defined in the appended claims is notnecessarily limited to the specific features or acts described. Rather,the specific features and acts are disclosed as illustrative forms ofimplementing the claims.

One skilled in the art will realize that a virtually unlimited number ofvariations to the above descriptions are possible, and that the examplesand the accompanying figures are merely to illustrate one or moreexamples of implementations.

It will be understood by those skilled in the art that various othermodifications may be made, and equivalents may be substituted, withoutdeparting from claimed subject matter. Additionally, many modificationsmay be made to adapt a particular situation to the teachings of claimedsubject matter without departing from the central concept describedherein. Therefore, it is intended that claimed subject matter not belimited to the particular embodiments disclosed, but that such claimedsubject matter may also include all embodiments falling within the scopeof the appended claims, and equivalents thereof.

In the detailed description above, numerous specific details are setforth to provide a thorough understanding of claimed subject matter.However, it will be understood by those skilled in the art that claimedsubject matter may be practiced without these specific details. In otherinstances, methods, apparatuses, or systems that would be known by oneof ordinary skill have not been described in detail so as not to obscureclaimed subject matter.

Reference throughout this specification to “one embodiment” or “anembodiment” may mean that a particular feature, structure, orcharacteristic described in connection with a particular embodiment maybe included in at least one embodiment of claimed subject matter. Thus,appearances of the phrase “in one embodiment” or “an embodiment” invarious places throughout this specification are not necessarilyintended to refer to the same embodiment or to any one particularembodiment described. Furthermore, it is to be understood thatparticular features, structures, or characteristics described may becombined in various ways in one or more embodiments. In general, ofcourse, these and other issues may vary with the particular context ofusage. Therefore, the particular context of the description or the usageof these terms may provide helpful guidance regarding inferences to bedrawn for that context.

What is claimed is:
 1. A method for fabricating an electrowettingdisplay, the method comprising: depositing a first spacer layer on asurface of a support plate, wherein the support plate includes asubstrate and an electrode layer, and wherein the first spacer layer atleast partially covers the substrate and the electrode layer; placing afirst mask layer on the first spacer layer, wherein the first mask layercovers one or more first portions of the first spacer layer; exposingone or more second portions of the first spacer layer to electromagneticenergy; placing a second spacer layer on the one or more second portionsof the first spacer layer and on the first mask layer; placing a secondmask layer on one or more first portions of the second spacer layer;exposing one or more second portions of the second spacer layer toelectromagnetic energy; and removing at least a portion of the one ormore second portions of the second spacer layer and at least a portionof the one or more second portions of the first spacer layer to formliquid ducts and a spacer grid on the support plate.
 2. The method ofclaim 1, wherein removing the at least the portion of the one or moresecond portions of the first spacer layer comprises: etching the atleast the portion of the one or more second portions of the first spacerlayer between the support plate and the one or more second portions ofthe second spacer layer.
 3. The method of claim 1, wherein the one ormore first portions of the first spacer layer and the one or more firstportions of the second spacer layer comprise rows and columns of spacerwalls, wherein the spacer walls partition a plurality of pixel regions.4. The method of claim 1, wherein placing the first mask layer on thefirst spacer layer comprises: depositing a light-absorbing black matrixmaterial to at least partially cover the one or more first portions ofthe first spacer layer.
 5. The method of claim 1, wherein the supportplate is a first support plate, and further comprising: joining thespacer grid onto pixel walls disposed on a second support plate.
 6. Amethod for fabricating an electrowetting display, the method comprising:depositing a first spacer layer on a support plate; placing a first masklayer on the first spacer layer; radiating portions of the first spacerlayer that are not covered by the first mask layer; depositing a secondspacer layer on the first spacer layer; placing a second mask layer onthe second spacer layer; radiating portions of the second spacer layerthat are not covered by the second mask layer; and etching the radiatedportions of the second spacer layer and the radiated portions of thefirst spacer layer to form a spacer grid comprising first spacerportions on the support plate and second spacer portions on the firstspacer portions.
 7. The method of claim 6, wherein etching the radiatedportions of the second spacer layer and the radiated portions of thefirst spacer layer results in the first mask layer remaining between thefirst spacer portions and the second spacer portions.
 8. The method ofclaim 6, wherein placing the first mask layer on the first spacer layercomprises: depositing a light-absorbing black matrix material to atleast partially cover the first spacer layer.
 9. The method of claim 6,wherein etching the radiated portions of the second spacer layer and theradiated portions of the first spacer layer comprises: under-etching thefirst spacer portion between the support plate and the second spacerportion to form liquid ducts.
 10. The method of claim 9, furthercomprising: forming pixel regions at least partially surrounded by fourwalls of the spacer grid by etching the radiated portions of the secondspacer layer and the radiated portions of the first spacer layer,wherein at least one of the four walls includes one or more of theliquid ducts.
 11. The method of claim 9, wherein etching the radiatedportions of the second spacer layer and the radiated portions of thefirst spacer layer comprises: forming the spacer grid such that thespacer grid is in contact with the support plate in crossed-shapedregions between the liquid ducts.
 12. The method of claim 9, furthercomprising: patterning the second mask layer such that a width of eachof the liquid ducts varies across an area of the support plate.
 13. Themethod of claim 6, wherein the support plate is a first support plate,and further comprising: joining the spacer grid onto pixel wallsdisposed on a second support plate.
 14. The method of claim 6, whereindepositing the second spacer layer on the first spacer layer compriseslaminating the second spacer layer on the first spacer layer.
 15. Anelectrowetting display comprising: a first support plate and a secondsupport plate opposite the first support plate; a first spacer layerdisposed on the second support plate, wherein the first spacer layerincludes channels; a second spacer layer disposed on the first spacerlayer, wherein the second spacer layer includes bridges that span acrossthe channels of the first spacer layer; a black matrix disposed betweenthe first spacer layer and the second spacer layer; and pixel wallsdisposed on the first support plate, wherein the pixel walls separateadjacent pixel regions from one another, and wherein the second spacerlayer is disposed on the pixel walls.
 16. The electrowetting display ofclaim 15, wherein the channels of the first spacer layer comprise anopen region configured to allow fluid to flow between two adjacent pixelregions.
 17. The electrowetting display of claim 15, wherein the firstspacer layer and the second spacer layer comprise materials differentfrom one another.
 18. The electrowetting display of claim 15, whereinone or more of widths, lengths, or shapes of the channels vary across anarea of the second support plate.
 19. The electrowetting display ofclaim 15, wherein the first spacer layer includes portions between thechannels, wherein the portions have cross-shapes.
 20. The electrowettingdisplay of claim 15, wherein each of the channels extends between thesecond support plate and the second spacer layer, and wherein each ofthe bridges separates one of the channels from one of the pixel walls.